[dart2dart] implement factory redirects

sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart_backend;
 
 class LocalPlaceholder {
   final String identifier;
   final Set<Node> nodes;
   LocalPlaceholder(this.identifier) : nodes = new Set<Node>();
@@ skipping 12 matching lines @@
     parameterIdentifiers.add(node.source.slowToString());
   }
 }
 
 class ConstructorPlaceholder {
   final Node node;
   final DartType type;
   final bool isRedirectingCall;
   ConstructorPlaceholder(this.node, this.type)
       : this.isRedirectingCall = false;
+  // Note: factory redirection is not redirecting call!
   ConstructorPlaceholder.redirectingCall(this.node)
       : this.type = null, this.isRedirectingCall = true;
 }
 
 class DeclarationTypePlaceholder {
   final TypeAnnotation typeNode;
   final bool requiresVar;
   DeclarationTypePlaceholder(this.typeNode, this.requiresVar);
 }
 
@@ skipping 125 matching lines @@
       declarationTypePlaceholders = new List<DeclarationTypePlaceholder>(),
       memberPlaceholders = new Map<String, Set<Identifier>>(),
       constructorPlaceholders =
           new Map<Element, List<ConstructorPlaceholder>>();
 
   void collectFunctionDeclarationPlaceholders(
       FunctionElement element, FunctionExpression node) {
     if (element.isGenerativeConstructor() || element.isFactoryConstructor()) {
       DartType type = element.getEnclosingClass().type.asRaw();
       makeConstructorPlaceholder(node.name, element, type);
+      Return bodyAsReturn = node.body.asReturn();
+      if (bodyAsReturn != null && bodyAsReturn.isRedirectingFactoryBody) {
+        // Factory redirection.
+        FunctionElement redirectTarget = element.defaultImplementation;
+        assert(redirectTarget != null && redirectTarget != element);
+        type = redirectTarget.getEnclosingClass().type.asRaw();
+        makeConstructorPlaceholder(
+            bodyAsReturn.expression, redirectTarget, type);
+      }
     } else if (Elements.isStaticOrTopLevel(element)) {
       // Note: this code should only rename private identifiers for class'
       // fields/getters/setters/methods.  Top-level identifiers are renamed
       // just to escape conflicts and that should be enough as we shouldn't
       // be able to resolve private identifiers for other libraries.
       makeElementPlaceholder(node.name, element);
     } else if (element.isMember()) {
       if (node.name is Identifier) {
         tryMakeMemberPlaceholder(node.name);
       } else {
@@ skipping 417 matching lines @@
 
   visitBlock(Block node) {
     for (Node statement in node.statements.nodes) {
       if (statement is VariableDefinitions) {
         makeVarDeclarationTypePlaceholder(statement);
       }
     }
     node.visitChildren(this);
   }
 }